It is proposed that Raman and Fourier transform infrared spectroscopy be applied to investigate the molecular mechanisms of light detection in normal and abnormal vision. It has been shown in a preliminary report (Rothschild et al., Science 191:1176, 1976) that the structure of photoreceptor membrane including the opsin protein, membrane lipids and retinylidene chromophore can be probed by using these techniques. By orienting the membranes into multibilayer stacks, additional information about the specific orientation of the protein skeletal structure, residues and other chemical groups can be deduced. In addition, picosecond mode-locked lasers in combination with Raman spectroscopy will allow extremely fast conformational changes in these membranes to be detected. Purified rod outer segments isolated from the retinas of RCS rats which suffer from retinitis pigmentosa will be studied using these techniques and compared to normal retinas. Measurements of light induced ion movement through the photoreceptor membrane will also be studied using voltage-sensitive fluorescent dyes which have been shown to be capable of detecting transmembrane potential changes in vesicles 500 A in diameter.